This invention relates to a protective switch device for power distribution systems and particularly to a vacuum fault interrupter and switch assembly including a positive contact operating mechanism connected to the movable contact of an interrupter.
In residential power distribution systems and the like interrupters or switching apparatus are incorporated into the system to provide automatic protection in response to abnormal load or line conditions and permit manual opening and closing of the circuit. The interrupters may advantageously seal the contacts in a vacuum enclosure with a movable contact having an operating member extending through a vacuum seal in the enclosure.
A vacuum interrupter unit has been widely employed in the prior art because it provides fast, low energy arc interruption with long contact life, low mechanical stress and a high degree of operating safety. Generally, the creation of the arc within a vacuum significantly extends the life of the contact and the interrupter when compared with oil filled interrupters. Vacuum interrupters further are not as affected by temperature and/or altitude. A spring loaded toggle mechanism is preferably coupled to the operating member for rapidly and positively opening and closing of the contacts. The toggle mechanism should minimize arcing while maintaining reliable contact engagement under normal service conditions. A manual control member or lever normally provides for resetting of the tripped mechanism as well as manual closure of the contacts and opening when necessary. The manual operating lever should be loaded to require positive positioning of a control lever and thereby prevent accidental actuation which should also be readily operated from a remote location. For example, if the switchgear is located within a below ground vault, the operating lever should be operable with a hook member from above the ground. With the recent development of underground distribution systems demand has risen for switchgear which can be mounted below as well as above the ground. For below ground installation, the switch gear must be designed to meet rigid specification which includes operation while submerged in ground contaminated water and the like. For example, the toggle mechanism and interrupter may be encased or encapsulated within an insulating material to totally encase the assembly.
The interrupter assembly should further be of a relatively rugged construction for use in various applications, while permitting convenient manipulation for installation, removal and maintenance. The interrupter unit in various different applications requires different toggle mechanisms. The interrupter unit is, in most installations, a vacuum enclosed type wherein the contacts are located within a vacuum bottle enclosure. The operating mechanism specification may differ with the installation. The interrupter unit and operating mechanism are, therefore, preferably separate devices with appropriate convenient connection.
Although various interrupters with spring loaded linkages have been suggested, there is a continuing need for an improvement in the construction of the actuating mechanism and the interrupter contact structure as such.